If you are trying to use System.Security.Cryptography.RSACryptoServiceProvider and are getting the following error:
System.Security.Cryptography.CryptographicException:
CryptoAPI cryptographic service provider (CSP) for this implementation
could not be acquired.
Please review this Microsoft Knowledge Base Article - 322371 Article ID: 210, Created On: 4/24/2009, Modified: 4/24/2009